During recent decades, a growing portion of the suturing required in surgical operations has been done with surgical staples formed in a variety of shapes for tasks such as the ligation of tubular structures and the closure of surgical incisions. The staples have generally been formed of a stainless steel which is compatible with living tissue, such that they can remain in place indefinitely.
Surgical stapling has benefitted not only the surgeon, by relieving him of much tedious conventional suturing with needle and silk or gut thread, but also the patient, since staple-suturing can significantly shorten the time required to carry out an operative procedure. As a result, the quantity of anesthetic required can be reduced, and the operative shock effect on the patient's nervous system can be minimized. In short, the prospect for a successful and rapid recovery can be increased by adopting the more rapid technique of staple-suturing.
Despite these benefits, staple-suturing is not without its shortcomings. In particular, the staple applicators in use are generally rather heavy and often clumsy affairs which are tiring for the surgeon to use. Further they are more expensive than is desirable for two reasons: (a) the mechanisms are surprisingly complex and demand considerable precision in manufacture if they are to work satisfactorily; (b) each type of staple applicator is intended for a fairly narrow range of suturing tasks, i.e., is specialized such that the applicator designed for tubal ligation is not satisfactory for the suturing of incisions in skin or fascia. As a result the number of different types of such applicators needed multiplies the cost of providing such equipment in each operating room. Another problem with existing applicators is the difficulty of clearly seeing the point of application of the staple because of the sheer bulk of the staple applicator. Finally, the requirement to maintain stringently aseptic conditions during surgery means that the staple applicator must be subjected to sterilization before each use. This requirement amounts to an additional complication and an added cost.
The above and other drawbacks of the prior art staple suturing techniques result principally from the use of mechanically deformed staples made typically of stainless steel. Since the forces required to deform such staples into a desired closed shape are high, the staple applicator must be provided with a mechanism capable of generating such forces. Consequently, mechanisms employing either gas under pressure, or manually applied force multiplied by a mechanical system of high "mechanical advantage" are found in the prior art. Either approach requires that the large forces generated be applied to the staple in such a way as to deform it into precisely the desired closed shape. The shape required upon closure depends, of course, on the task for which the applicator is intended, such that the design of the applicator must be correspondingly different for the various suturing tasks.
As will appear from the remainder of this application, the above and many other persistent problems of the prior art staple-suturing methods and apparatuses could be solved if the means of deforming the staple from an open to a closed shape required the application of no more force than is required to hold the staple in position at the site of the suturing. Moreover, if the means of deforming the staple could be independent of the desired final shape of the staple, much of the burden of providing many different types of staple applicators for the different types of suturing could be eliminated.